Architectures for light emitting diode (LED) lighting systems

ABSTRACT

Various embodiments relate to systems and methods for controlling one or more LED-based lighting sources that are coupled to a logic module by a ribbon cable. The ribbon cable allows some or all of the processing components (e.g., processors and drivers) to be decoupled from the LED-based lighting source(s). The processing components can instead be housed within the logic module, which is able to simultaneously control the LED-based lighting source(s). Together with color models established for each LED board, the logic module acts as a platform for modularity and is able to more precisely control the color channels of each LED-based lighting source using the color models established for those LED-based lighting source(s). Techniques are also described herein that allow the logic module to utilize data stored within an erasable programmable read-only memory (EPROM) that describes the color characteristics of an LED-based lighting source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-in-Part of U.S. patent applicationSer. No. 14/458,457, entitled “Architecture of a Tunable Lamp System”and filed Aug. 14, 2014. This application claims priority to and thebenefit of U.S. Provisional Application No. 62/269,045, entitled“Architectures for Light Emitting Diode (LED) Lighting Systems” andfiled on Dec. 17, 2015. Both U.S. patent application Ser. No. 14/458,457and U.S. Provisional Application No. 62/269,045 are incorporated byreference in their entirety.

FIELD OF THE INVENTION

Various embodiments concern hardware architectures for lighting systemsand, more specifically, techniques for designing and controllinglighting systems.

BACKGROUND

Traditional lighting systems typically rely on conventional lightingtechnologies, such as incandescent bulbs and fluorescent bulbs. Butthese light sources suffer from several drawbacks. For example, suchlight sources do not offer long life or high energy efficiency.Moreover, such light sources offer only a limited selection of colors,and the color of light output by these light sources generally changesover time as the bulbs age and begin to degrade. Consequently, lightemitting diodes (LEDs) have become an attractive option for manyapplications. The vast majority of LED-based lighting systems, however,use fixed white LEDs with no tunable range.

Although LED-based systems are capable of having longer lives andoffering high energy efficiency, several issues still exist includingthe degradation of color over time and the responsiveness of colortuning adjustments. These issues can be compounded when multipleLED-based lighting systems are placed near one another or are coupleddirectly to one another.

Moreover, printed circuit board assemblies (PCBAs) with LEDs oftenexhibit undesirable acoustic effects when the PCBAs are driven atparticular (e.g., resonant) frequencies in the human hearing range(e.g., approximately 50 Hz to 25 kHz). For instance, sound may beproduced by vibrating capacitors, such as piezoelectric ceramiccapacitors that change dimensions in response to an applied voltage.Some inductors may also create noise by magnetostriction. Althoughsolutions (e.g., specialty dampeners, low drive acoustic capacitors)have been proposed in an effort to reduce or eliminate these acousticeffects, this problem continues to plague PCBAs regardless ofapplication (i.e., not just when used as part of a lighting system).

A light source can be characterized by its color temperature and by itscolor rendering index (CRI). The color temperature of a light source isthe temperature at which the color of light emitted from a heated blackbody radiator is matched by the color of the light source. For a lightsource that does not substantially emulate a black body radiator, suchas a fluorescent bulb or LED, the correlated color temperature (CCT) ofthe light source is the temperature at which the color of light emittedfrom a heated black body radiator is approximated by the color of thelight source.

The CCT can also be used to represent chromaticity of white lightsources. But because chromaticity is two-dimensional, Duv (as defined inANSI C78.377) can be used to provide another dimension. When used with aMacAdam ellipse (which represents the colors distinguishable to thehuman eye), the CCT and Duv allow the visible color output by anLED-based lighting system to be more precisely controlled (e.g., bybeing tuned).

The CRI, meanwhile, is a rating system that measures the accuracy of howwell a light source reproduces the color of an illuminated object incomparison to an ideal or natural light source. The CRI is determinedbased on an average of eight different colors (R1-R8). A ninth color(R9) is a fully saturated test color that is not used in calculatingCRI, but can be used to more accurately mix and reproduce the othercolors. The CCT and CRI of LEDs is typically difficult to tune andadjust. Further difficulty arises when trying to maintain an acceptableCRI while varying the CCT of an LED.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects, features, and characteristics will become more apparentto those skilled in the art from a study of the following DetailedDescription in conjunction with the appended claims and drawings, all ofwhich form a part of this specification. While the accompanying drawingsinclude illustrations of various embodiments, the drawings are notintended to limit the claimed subject matter.

FIG. 1A depicts one example of an LED-based lighting system thatincludes an LED-based light source (e.g., an LED board) coupled to alogic module by a ribbon cable as may occur in some embodiments.

FIG. 1B depicts another example of an LED-based lighting system as mayoccur in some embodiments.

FIG. 1C is a bottom cutaway view of the LED-based lighting system shownin FIG. 1B.

FIG. 1D depicts one example of an LED-based light source that could becoupled to a logic module.

FIG. 2A depicts a logic module that includes a mounting plate and amotherboard that can be coupled to one or more daughterboards (e.g., viaa daughterboard connector).

FIG. 2B depicts a cutaway drawing of the logic module shown in FIG. 2A.

FIG. 2C illustrates how the logic module may include one or more portsfor receiving cables for transferring power, data, etc.

FIG. 2D depicts one example of a logic module having a cavity forretaining a daughterboard that enables a certain functionality.

FIG. 2E depicts another example of a logic module coupled to adaughterboard.

FIG. 2F depicts another example of a logic module coupled to adaughterboard.

FIG. 3 is a generalized block diagram of a lighting system that includesa series of LED boards, each having an EPROM.

FIG. 4 depicts a process for handling the “un-binned” LEDs of one ormore LED boards coupled to a logic module.

FIG. 5 depicts a user interface whose functionality can be mimickedusing spectral power distributions (SPDs) stored within the EPROM(s) ofthe LED board(s).

FIG. 6A is a high-level block diagram of an LED-based lighting systemthat includes a logic module connected to one or more LED boards.

FIG. 6B is another high-level block diagrams of an LED-based lightingsystem that includes a logic module connected to one or more LED boards.

FIG. 7 depicts a process for controllably tuning one or more LED boardsusing a logic module.

FIG. 8 is a block diagram illustrating an example of a computer systemin which at least some operations described herein can be implemented.

The figures depict various embodiments for the purposes of illustrationonly. While specific embodiments have been shown by way of example inthe drawings and are described in detail below, the embodiments areamenable to various modifications and alternative forms. The intentionis not to limit the disclosure to the particular embodiments described.Accordingly, the claimed subject matter is intended to cover allmodifications, equivalents, and alternatives falling within the scope ofthe invention as defined by the appended claims.

DETAILED DESCRIPTION

Various embodiments are described herein that relate to techniques forcontrolling lighting systems. More specifically, various embodimentsrelate to systems and methods for controlling light emitting diode (LED)boards, fixtures, etc., that are coupled to a logic module by a ribboncable. The ribbon cable allows some or all of the processing components(e.g., processors and drivers) to be decoupled from the LED board. Theaforementioned processing components can instead be housed within thelogic module, which is able to simultaneously control one or more LEDboards. Together with color models established for each LED board, thelogic module acts as a platform for modularity and is able to moreprecisely control the color channels of each LED board using the colormodels established for that board. A “color channel” refers to the oneor more LEDs of a particular color on an LED board. Therefore, an LEDboard having five color channels includes LEDs of five different colors.

Techniques are also described herein that allow the logic module toutilize data describing the color characteristics (e.g., color model,spectral power distribution, tristimulus values) of an LED board.Generally, the data is stored within the erasable programmable read-onlymemory (EPROM) coupled directly to the LED board; however, one skilledin the art will recognize that any other suitable form of memory mayalso be used (e.g., an LED board may include flash memory rather than anEPROM). However, in some embodiments, the LED board may be configured towirelessly store and/or retrieve the data from a cloud-based storagesolution (e.g., via Bluetooth, Near Field Communication (NFC), Wi-Fi, orsome other wireless communication channel). Low resolution versions ofthe spectral power distribution (SPD) of a particular LED board atvarious operating conditions can be created and stored within the EPROM.These low resolution versions can then be retrieved by the logic modulefrom the EPROM and used to better control the mixing of the colorchannels of the LED board and improve visible output. Color model(s)and/or tristimulus value(s) could also be stored within the EPROM forretrieval by the logic module.

The technologies introduced herein can be embodied as special-purposehardware (e.g., circuitry), as programmable circuitry appropriatelyprogrammed with software and/or firmware, or as a combination ofspecial-purpose and programmable circuitry. Hence, embodiments mayinclude a machine-readable medium having stored thereon instructionswhich may be used to program a computer (or another electronic device)to perform a process. The machine-readable medium may include, but isnot limited to, floppy diskettes, optical disks, compact disk read-onlymemories (CD-ROMs), magneto-optical disks, read-only memories (ROMs),random access memories (RAMs), EPROMs, electrically erasableprogrammable read-only memories (EEPROMs), magnetic or optical cards,flash memory, or any other type of media/machine-readable mediumsuitable for storing electronic instructions.

Terminology

Brief definitions of terms, abbreviations, and phrases used throughoutthis application are given below.

Reference in this specification to “one embodiment” or “an embodiment”means that a particular feature, structure, or characteristic describedin connection with the embodiment is included in at least one embodimentof the disclosure. The appearances of the phrase “in one embodiment” or“in some embodiments” in various places in the specification are notnecessarily all referring to the same embodiment(s), nor are separate oralternative embodiments mutually exclusive of other embodiments.Moreover, various features are described which may be exhibited by someembodiments and not by others. Similarly, various requirements aredescribed which may be requirements for some embodiments but not otherembodiments.

Unless the context clearly requires otherwise, throughout the DetailedDescription and the claims, the words “comprise,” “comprising,” and thelike are to be construed in an inclusive sense, as opposed to anexclusive or exhaustive sense; that is to say, in the sense of“including, but not limited to.” As used herein, the terms “connected,”“coupled,” or any variant thereof, means any connection or coupling,either direct or indirect, between two or more elements; the coupling orconnection between the elements can be physical, logical, or acombination thereof. For example, two devices may be coupled directly toone another, or via one or more intermediary channels or devices. Asanother example, devices may be coupled in such a way that informationcan be passed there between, while not sharing any physical connectionwith one another.

Additionally, the words “herein,” “above,” “below,” and words of similarimport, when used in this application, shall refer to this applicationas a whole and not to any particular portions of this application. Wherethe context permits, words in the Detailed Description using thesingular or plural number may also include the plural or singular numberrespectively. The word “or,” in reference to a list of two or moreitems, covers all of the following interpretations of the word: any ofthe items in the list, all of the items in the list, and any combinationof the items in the list.

If the specification states a component or feature “may,” “can,”“could,” or “might” be included or have a characteristic, thatparticular component or feature is not required to be included or havethe characteristic.

The term “module” refers broadly to software, hardware, or firmware (orany combination thereof) components. Modules are typically functionalcomponents that can generate useful data or other output using specifiedinput(s). A module may or may not be self-contained.

The terminology used in the Detailed Description is intended to beinterpreted in its broadest reasonable manner, even though it is beingused in conjunction with certain examples. The terms used in thisspecification generally have their ordinary meanings in the art, withinthe context of the disclosure, and in the specific context where eachterm is used. For convenience, certain terms may be highlighted usingcapitalization, italics, and/or quotation marks. The use of highlightinghas no influence on the scope and meaning of a term. The scope andmeaning of a term is the same, in the same context, whether or not it ishighlighted. It will be appreciated that the same element can bedescribed in more than one way.

Consequently, alternative language and synonyms may be used for any oneor more of the terms discussed herein. However, special significance isnot to be placed upon whether or not a term is elaborated or discussedherein. Synonyms for certain terms are provided. A recital of one ormore synonyms does not exclude the use of other synonyms. The use ofexamples anywhere in this specification, including examples of any termsdiscussed herein, is illustrative only and is not intended to furtherlimit the scope and meaning of the disclosure or of any exemplifiedterm. Likewise, the disclosure is not limited to the various embodimentsgiven in this specification.

System Topology Overview

FIGS. 1A-D depict examples of LED-based lighting systems 100 thatinclude an LED-based light source, such as an LED board 102 or an LEDfixture 112, coupled to a logic module 104 (which may also be referredto as a color tuning module) by a ribbon cable 106. By separating one ormore processing components (e.g., processors, drivers, power couplings)from the LED-based light source, the techniques described herein enablethe necessary driver(s), processor(s), etc., to be housed within thelogic module 104 rather than on the LED-based light source.Consequently, an LED board 102 can be intelligently controlled by thelogic module 104, despite the LED board 102 not retaining the necessarycomponents itself. As will be further described below with respect toFIG. 3, these techniques also allow a single logic module 102 tosimultaneously control multiple LED boards or fixtures, each of whichmay be coupled to the logic module 104 by a separate ribbon cable.Further details regarding possible system architectures of tunable lampsystems can be found in co-pending U.S. application Ser. No. 14/458,457,which is incorporated herein by reference in its entirety.

Although the LED board 102 is illustrated by FIG. 1 as an array of LEDs108 positioned linearly on a substrate, other arrangements are alsopossible and, in some cases, may be preferable. For example, an LEDboard 102 or an LED fixture 112 may include a circular arrangement orcluster of mid-power LEDs, a single high power LED, or some otherlighting feature.

Conventionally, a group of LED boards are serially coupled to oneanother and any processing and/or multiplexing would be performedlocally (e.g., by the drivers present on each LED board). But this cancause several issues. For example, the processing components aredistributed amongst the group of LED boards, rather than consolidatedinto a single structural component, which makes identifying problems andservicing those processing components more difficult. Moreover, addingprocessing components to each LED board increases production cost, thetotal power needed by the LED board, the heat generated by the LED boardduring use, the total space consumed by (i.e., the footprint of) the LEDboard, etc. By coupling the LED board 102 to a distinct logic module104, processing can instead be performed remotely (i.e., not on or bythe LED board 102 itself), which solves many of the aforementionedproblems.

Note, however, that the LED board 102 could include one or morecomponents for intelligently controlling how light is emitted. Forexample, the LED board 102 may include a dedicated memory and amicroprocessor that is able to communicate with the logic module 104. Insome embodiments, the LED board 102 also includes a communication modulethat enables the LED board 102 to communicate via a wirelesstransmission protocol (e.g., Bluetooth, NFC, or Wi-Fi). Accordingly, theprocessing components (e.g., processors, drivers, power couplings) forthe LED-based lighting system 100 may be distributed across the logicmodule 104 and the LED board 102. As further described below, such anarrangement allows logic modules and LED-based light sources (e.g., LEDboards and LED fixtures) to be used interchangeably with one another.

The ribbon cable 106 allows the processing components (e.g., drivers,processors) to be physically decoupled from the LED board 102. Theribbon cable 106 shown here includes conducting wires running parallelto one another on the same flat plane, although round ribbon cablescould also be used in some embodiments. Whether the ribbon cable 106 iswide and flat (as shown here) or bundled together in a cord may dependon constraints imposed on the lighting system 100 by the localenvironment, such as the available space and the route to be taken bythe ribbon cable 106 (e.g., through a lighting troffer). Moreover, insome embodiments, the LED board 102 and logic module 104 may eachinclude one or more modules for wirelessly transmitting data, power,etc., that render the ribbon cable 106 partially or entirelyunnecessary.

The ribbon cable 106, which carries a mix of analog and digital signals,can include a series of wires adapted for different purposes. Forexample, the ribbon cable 106 can include two wires that carry avariable current signal and a pulse-width modulation (PWM) signal foreach color channel (that together form a high/low differential pair),one or more wires for photodiodes that provide optical feedback, one ormore wires for thermistors that provide thermal feedback, one or morewires that serve as ground(s) for the thermistor(s), and one or morewires for an EPROM (e.g., separate wires for a power signal, clocksignal, and data signal) positioned on the LED board 102. Otherembodiments can include some subset of these wires and/or additionalwires.

As further described below, the wire(s) corresponding to the EPROM allowthe logic module 104 to retrieve data from the EPROM that specifies, forexample, color characteristics of the LEDs on the LED board 102. Thethermistors 114 and photodiodes 116, meanwhile, can be used to measurethermal and optical feedback, respectively. For example, the thermistorsmay be used to measure thermal feedback initially, and then after theexpiration of a predetermined time period, the photodiodes may be usedto measure the optical feedback to see whether aging has affected theoutput of the LEDs. The ground wire(s) could be distinct from oneanother (e.g., a different ground for each thermistor) or shared (e.g.,a single ground wire shared between two thermistors).

Using a ribbon cable 106 to couple the LED board 102 to the logic module104 also allows a user to clamp the ribbon cable 106 and streamreplicated signals to one or more other LED boards. Clamping the ribboncable 106 allows the logic module 104 to simultaneously control a seriesof LED boards that have been physically and logically linked together.

Oftentimes, the logic module 104 is configured to receive the ribboncable 106 (or multiple ribbon cables) at different locations. Forexample, the logic module 104 may have multiple ribbon cable ports onone side of the structure (e.g., stacked adjacent to one another) or onmultiple sides of the structure (e.g., a single port positioned on eachend of the logic module 104). The design of the logic module 104 mayalso depend on the mounting scheme intended to be used by the logicmodule 104 (e.g., within a light enclosure or lighting troffer).

The LED board 102 can be composed of any suitable substrate backing 110able to appropriately dissipate heat generated by the LEDs 108. Specificnon-metal substrates, such as a woven fiberglass cloth with an epoxyresin binder (e.g., FR4), may be used to reduce or eliminate variousproblems associated with metal substrates. For example, a substratebacking 110 composed of FR4 can more efficiently dissipate the heatgenerated by multiple color channels and not experience the heatretention issues typically encountered by metal substrates. The use ofFR4 is enabled by the use of mid-power LEDs, rather than high-powerLEDs, which typically require a metal substrate. As another example, FR4can be more easily divided into separate layers for each color channel.

FIGS. 2A-F depict several different embodiments of logic modules 200that include a mounting plate 206 and a motherboard 202, which can becoupled to one or more daughterboards 204 (e.g., via a daughterboardconnector). As further described below, installation of a daughterboard204 enables an additional feature/functionality on the logic module 200,such as the ability to communicate with LED boards via a particularcommunication protocol. The motherboard 202 can include a power adapter,one or more incoming signal connectors 210 (e.g., as RJ45 connectorconfigured to receive DMX input control signals), a ribbon cable port208 for receiving a ribbon cable, etc. These components and connectorscan be arranged on any of the sides of the logic module 200.

As noted above, conventional LED-based light sources that includeprocessing components are limited in the amount of power they canreceive. The LED-based lighting systems described here, however, are notlimited in such a manner because the processing components are stored inthe logic module 200 rather than on the LED-based light source (e.g.,LED boards or LED fixtures). Because power is provided directly to thelogic module 200, the total amount of supplied power can be increased(e.g., up to 80 watts), which allows the logic module 200 to be coupledto and simultaneously tune the color of multiple LED boards (e.g., 8 ormore LED boards at a time). This is particularly advantageous when theamount of available space is limited within a light enclosure orlighting troffer.

Removing the processing components from the LED-based light sourcesallows space to be more efficiently utilized within the light enclosureor lighting troffer. For example, removal of the processing componentsenables the dimensions of an LED board to be decreased.

The logic module 200 may be configured to support several basicfunctions without any daughterboards 204 needing to be installed. Forexample, Bluetooth and DMX signals may be receivable by an unmodifiedlogic module 200 (i.e., a logic module that does not include anydaughterboards). Other components, such as a power supply or amodule/connector for a proprietary control technology, could also beadded to the logic module 200 to enable additional features orfunctionalities. The logic module 200 effectively serves as a modifiableinterface that allows LEDs to be more readily and precisely controlled.

Partitioning of the logic module 200 allows the motherboard 202 to becoupled to one or more daughterboards 204 (e.g., modules) that provide aparticular functionality. Said another way, the logic module 200 acts asa partitioned platform that enables modularity of a system forcontrolling LEDs. The daughterboard(s) 204 could, for example, allow thelogic module 200 to communicate in accordance with a certaincommunication protocol. In some embodiments, multiple daughterboards canbe “stacked” (i.e., simultaneously coupled to the logic module 200),thereby providing multiple functionalities. The modularmotherboard-daughterboard design discussed here allows the logic module200 to be readily re-configured after the logic module 200 has beeninstalled. For example, the logic module could be adapted to communicatein accordance with a different protocol after being installed within atroffer. These post-installation reconfigurations are not possible inconventional lighting systems.

This architecture can also provide other unique benefits. For example,the logic module 200 may include a port (e.g., for Ethernet) in or nearthe daughterboard connector 208 (or within the daughterboard 204itself).

EPROM Feedback

FIG. 3 is a generalized block diagram of a lighting system 300 thatincludes a series of LED boards 308 a-d, each having a unique EPROM 310a-d. The series of LED boards 310 a-d is controlled by a single logicmodule 302 that determines how to manage (e.g., controllably tune thecolor of) the LEDs on each board. This issue does not plagueconventional control systems because those systems instead place thenecessary processing components (e.g., processors 304 and drivers 306)on each individual LED board 308 a-d.

The logic module 302 preferably considers the characteristics of thecolor channels on each LED board when controllably tuning the lightingsystem 300 as a whole. For example, it may be desirable to merge a colormodel stored in the EPROMs 310 a-b of each LED board 308 a-d in acertain manner to more effectively control the LEDs. The ability toretrieve and analyze board-specific color information takes onadditional importance when the logic module 302 receives feedback frommultiple LED boards 308 a-d.

For example, the logic module 302 may receive a signal from each LEDboard 308 a-d that specifies a characteristic (e.g., product number orname) that uniquely identifies the corresponding LED board. As anotherexample, the logic module 302 may receive isolated feedback for each LEDboard 308 a-d by selectively turning off whichever color channel(s) thelogic module 302 is not communicating with at a given point in time. Theisolated feedback received for each LED board could affect how the logicmodule 302 controls the group of LED boards 308 a-d as a whole. Theisolated feedback could also be used to identify a particular LED boardthat needs to be replaced because, for example, the visibility output ofthe LEDs has fundamentally shifted due to production over time or theforward voltage (V_(f)) has dropped.

For each LED board 308 a-d, a static color model can be created based ona reasonable sample of “un-binned” LEDs in a set configuration, asdescribed in co-pending U.S. application Ser. No. 13/766,707, which isincorporated herein by reference in its entirety. Oftentimes, it isdesirable to examine the difference between an average of “n” colormodels and a color model created from an average of “n” sets of spectralpower distributions (SPDs), where “n” represents an integer value.

When a color model generated from a set of averaged SPDs produces areasonable result, the required SPDs can be stored (e.g., in a reduceddata format) in the EPROM 310 a-d of the corresponding LED board 308 a-din a reduced data format. For instance, one reduced data formatdescribed herein is the SPD quantized integer (SQUINT) format. The setof required SPDs can then be used for research, testing, etc. In such ascenario, each LED board 308 a-d includes its own SPD characterizationstored within its own EPROM 310 a-d. Other information characterizing anLED board, such as various color models, tristimulus values, and forwardvoltages, could also be stored in the corresponding EPROM in a normal orreduced data format.

In some embodiments, each SPD distribution summary further characterizesa corresponding color string with tristimulus values across differentelectric current values and temperature values when light produced bythe corresponding color string is reflected off of the differentconventional color cards (e.g., Color Rendering Index, Color QualityScale, or TM30, which measures color rendering based on a comparison toa color palette of 99 colors).

Each SPD distribution summary may also include a thermal matrix thatcharacterizes thermal cross-talk and capacity characteristics ofadjacent light sources in the corresponding color string. In suchembodiments, the thermal matrix may be transmitted from the LED board tothe logic module, which considers the terminal matrix whenre-calibrating the color model.

When the lighting system 300 is powered on, the logic module 302 candetermine which LED boards 308 a-d are attached to the logic module 302.If a new LED board (or new set of LED boards) is detected, the reduceddata files (e.g., reduced SPDs) are read from the EPROM(s) of those newLED board(s) by the logic module 302, and an appropriate adjustment canbe made to the color model employed by the logic module 302 based on thedesired target and any differences between the ideal SPD(s) and theaverage of the SPDs stored by the attached LED boards 310 a-d. Forexample, the logic module 302 may selectively tune the color one or moreparticular LED boards 308 a-d to more accurately replicate a desiredcolor model.

One skilled in the art will recognize that the information stored withinthe reduced data files could be conveyed in several different ways. Forexample, SPD information for a given LED board could be captured withina unique visual design that is printed or affixed to an LED board. Theunique visual design could be, for example, a barcode or Quick Response(QR) code. In such embodiments, the SPD information can be stored in anetwork-accessible storage medium (and conveyed by the unique visualdesign) rather than a file stored within an EPROM of the LED board.

Moreover, using a unique visual design to convey such information mayeliminate the need for the LED board and logic module to communicatedirectly with one another. For example, scanning the unique visualdesign on an LED board may prompt a network-accessible control system(also referred to as a “cloud-based control system”) to wirelesslytransmit the appropriate information directly to a corresponding logicmodule. Wireless reception of the information may be enabled by adaughterboard that is connected to the corresponding logic module.

FIG. 4 depicts a process 400 for handling the “un-binned” LEDs of one ormore LED boards that are coupled to a logic module. In some embodiments,rather than store a full SPD graph in the EPROM of each LED board, a lowresolution version of the SPD (i.e., a “reduced SPD”) is created andstored in the EPROM. A full SPD graph tends to be fairly large, while areduced SPD typically comprises less than 100 bytes of data. Because theSPD characterizes all of the color channels on an LED board under aparticular set of operating parameters (e.g., temperature, power level),it may be desirable to create and store multiple reduced SPDs thatrepresent a variety of possible scenarios. That is, a single SPDrepresents the color characteristics of one or more color channels undera particular set of operating conditions (e.g., temperature, drivingcurrent).

More specifically, a reduced SPD can be created by using a reducednumber of nanometer buckets (e.g., 5 nanometer). Rather than track thepower in each particular wavelength range with a floating number, thewavelengths are normalized (e.g., by dividing by the peak wavelength inthe SPD), and the normalized wavelengths are mapped to a 0-255 scale.Any negative numbers may be disregarded and treated as zeroes duringthis process. Thus, each wavelength “bucket” includes a single byte. Bythrowing out all measurements less than 400 nanometers and greater than800 nanometers, the full SPD can be characterized in a much simplermanner that is still sufficient for many calculations. Other wavelengthranges could be used in alternative embodiments.

Because the total compression of the full SPD graph is substantial(e.g., nearly 40×), a wide variety of spectral data for each LED boardat various power levels and temperature settings can be stored withinthe EPROM. The LED board, therefore, can effectively carry a virtualspectrometer of its initial state and provide virtual spectrographicfeedback using a library of reduced SPDs corresponding to variousoperating conditions. When the LED board is coupled to a logic modulethat controls one or more other LED boards, the spectral data of thereduced SPDs can be used by the logic module to better control the setof LED boards (e.g., by making modifications based on operatingtemperature, power level, etc.).

The reduced SPDs could be used by a lighting system in various ways. Forexample, a logic module may determine (e.g., using one or morethermistors) the operating temperature of each of a series of LEDboards, average the operating temperatures, and identify the reduced SPDcorresponding to the average operating temperature of the lightingsystem as a whole. Alternatively, the logic module could determine theoperating temperature of each LED board in the set, identify a reducedSPD for each LED board based on the operating temperature of thecorresponding LED board, and combine the reduced SPDs in some manner.The reduced SPD(s) identified by the logic module may be used todetermine whether/how to tune the color of particular LED boards in alighting system.

Because the reduced SPDs embody virtualized static models, the logicmodule is able to more effectively control the LED boards by simulatingfull spectrographic feedback. However, in some embodiments, the reducedSPDs could also be used to determine compliance with certain operatingconditions, such as temperature. For example, the logic module may beconfigured to monitor the operating temperature based on which reducedSPDs have been used over a certain time period.

The process 400, therefore, requires that a robust color model begenerated based on the expected characteristics of the LEDs on aparticular LED board of the lighting system (step 402). The robust colormodel includes a series of reduced SPDs, where each reduced SPDrepresents a characterization of the LEDs of the particular LED board ata certain set of operating conditions (e.g., temperature, power level).The LED characterizations (i.e., the reduced SPDs or SQUINT files) arethen stored in the EPROM of the particular LED board (step 404). EachSQUINT file represents the spectral density distribution of one or moreLEDs of a single color.

When the particular LED board is implemented as part of a lightingsystem, a logic module may retrieve one or more reduced SPDs from theEPROM of the particular LED board (step 406), and then use the reducedSPD(s) to make corrective adjustments to the color model implemented bythe logic module for the lighting system as a whole (step 408). Morespecifically, the logic module may make corrective adjustments to theparticular LED board or to the lighting system as a whole (i.e., toother LED boards included in the lighting system). For example, thelogic module may be configured to “trim” (i.e., modify) the color modelwithout recalculating the color model in its entirety.

FIG. 5 depicts a user interface whose functionality can be mimickedusing SPDs stored within the EPROM(s) of the LED board(s). Using theinterface, flux ratio(s) for set(s) of color channels can be readilydetermined by identifying the available colors (under “Display Name”),the quantity (under “Qty”) of each color, minimum and maximum inputcurrent (under “Max mA” and Min mA”), etc. As shown in FIG. 5, triads ofdifferent colors can be identified, as well as the optimal flux ratiofor each set, based on CCT (and vice versa). Said another way, theinterface allows the characteristics of color LED(s) to be readilydetermined by specifying the operating conditions.

More specifically, to determine an “optimal” ratio corresponding to aparticular CCT, the flux ratio is determined for each color set. If morethan three color channels are used, there are generally many solutions,some of which have better CRI values or energy efficiency values. Notethat as the number of color channels increases, the number ofcalculations and possibly solutions increases dramatically. CRI valueshave been used in the context of specific examples for the purposes ofillustration only. One skilled in the art will recognize that othermodels may be used to communicate a light source's color renderingproperties, such as TM-30-15 as approved by the Illuminating EngineeringSociety (IES). The method described by IES TM-30-15 (also referred to as“TM-30”) encompasses several individual measures and graphics thatcomplement one another and provide a comprehensive characterization ofhow light will affect the color appearance of objects. These measuresinclude the Fidelity Index (R_(f)), Gamut Index (R_(g)), and ColorVector Graphic.

As the optics age (e.g., as the LEDs themselves age, or the LED coversand other optical elements degrade), color sets may need to be replaced.Accordingly, the LED-based lighting system (e.g., logic module) may needto re-determine the optimal flux ratios of each color set.Conventionally, maintaining proper color mixing after replacement wassimply not possible because the process was computationally intensiveand the proper data was unavailable. Here, however, heuristics and theSPD files can be used to mimic the functionality of the interfacedescribed above and thus re-determine the optical flux ratios.

Lighting System Topology

FIGS. 6A-B are high-level block diagrams of an LED-based lighting systemthat includes a logic module connected to one or more LED boards, whileFIG. 7 depicts a process for controllably tuning one or more LED boardsusing a logic module.

One or more input signals (e.g., input voltage, DMX, Bluetooth) arereceived by the logic module and relayed to one or more processingcomponents. The processing component(s) can include, for example, amicroprocessor, field-programmable gate array (FPGA), etc. In someembodiments, some or all of the input signal(s) are conditioned (e.g.,by a signal conditioning module) before being provided to the processingcomponent(s). For example, input signal(s) (e.g., pulse width modulatedsignals) for controlling each color channel of an LED board may bedithered to address several different issues. For instance, setting thefrequency of a modulated input signal to a higher value (e.g., 25 kHzrather than 1 kHz) may eliminates acoustic noise and electronic flicker(also referred to as “e-flicker”) that causes visible changes in thebrightness of an electronic display (e.g., the screen of a mobilephone). E-flicker can be particularly problematic when trying to capturevideo of a scene due to a mismatch between the frame rate and the camerashutter speed.

As noted above, input signal(s) prompt the logic module to control oneor more LED boards in a certain manner. For example, the processingcomponent(s) may selectively control a control signal driver and/or apower driver that interface with the LED board(s).

In some embodiments, the logic module selectively controls a primary LEDboard (e.g., using the control signal driver and/or power driver) thatis coupled to a secondary LED board. For example, the primary LED boardcould be coupled to the secondary LED board by a smart connector thatcauses the driver signals provided to the primary LED board by the logicmodule to also be provided to the secondary LED board. Similarly, thesecondary LED board may be coupled to additional secondary LED board(s)that act in unison with the primary LED board.

Computer System

FIG. 8 is a block diagram illustrating an example of a computing system800 in which at least some operations described herein can beimplemented. The computing system may include one or more centralprocessing units (“processors”) 802, main memory 806, non-volatilememory 810, network adapter 812 (e.g., network interfaces), videodisplay 818, input/output devices 820, control device 822 (e.g.,keyboard and pointing devices), drive unit 824 including a storagemedium 526, and signal generation device 830 that are communicativelyconnected to a bus 816. The bus 816 is illustrated as an abstractionthat represents any one or more separate physical buses, point to pointconnections, or both connected by appropriate bridges, adapters, orcontrollers. The bus 816, therefore, can include, for example, a systembus, a Peripheral Component Interconnect (PCI) bus or PCI-Express bus, aHyperTransport or industry standard architecture (ISA) bus, a smallcomputer system interface (SCSI) bus, a universal serial bus (USB), IIC(I2C) bus, or an Institute of Electrical and Electronics Engineers(IEEE) standard 1394 bus, also called “Firewire.”

In various embodiments, the computing system 800 operates as astandalone device, although the computing system 800 may be connected(e.g., wired or wirelessly) to other machines. In a networkeddeployment, the computing system 800 may operate in the capacity of aserver or a client machine in a client-server network environment, or asa peer machine in a peer-to-peer (or distributed) network environment.

The computing system 800 may be a server computer, a client computer, apersonal computer (PC), a user device, a tablet PC, a laptop computer, apersonal digital assistant (PDA), a cellular telephone, an iPhone, aniPad, a Blackberry, a processor, a telephone, a web appliance, a networkrouter, switch or bridge, a console, a hand-held console, a gamingdevice, a music player, any portable/mobile/hand-held device, or anymachine capable of executing a set of instructions (sequential orotherwise) that specify actions to be taken by the computing system.

While the main memory 806, non-volatile memory 810, and storage medium826 (also called a “machine-readable medium) are shown to be a singlemedium, the term “machine-readable medium” and “storage medium” shouldbe taken to include a single medium or multiple media (e.g., acentralized or distributed database, and/or associated caches andservers) that store one or more sets of instructions 828. The term“machine-readable medium” and “storage medium” shall also be taken toinclude any medium that is capable of storing, encoding, or carrying aset of instructions for execution by the computing system and that causethe computing system to perform any one or more of the methodologies ofthe presently disclosed embodiments.

In general, the routines executed to implement the embodiments of thedisclosure, may be implemented as part of an operating system or aspecific application, component, program, object, module or sequence ofinstructions referred to as “computer programs.” The computer programstypically comprise one or more instructions (e.g., instructions 804,808, 828) set at various times in various memory and storage devices ina computer, and that, when read and executed by one or more processingunits or processors 802, cause the computing system 800 to performoperations to execute elements involving the various aspects of thedisclosure.

Moreover, while embodiments have been described in the context of fullyfunctioning computers and computer systems, those skilled in the artwill appreciate that the various embodiments are capable of beingdistributed as a program product in a variety of forms, and that thedisclosure applies equally regardless of the particular type of machineor computer-readable media used to actually effect the distribution.

Further examples of machine-readable storage media, machine-readablemedia, or computer-readable (storage) media include, but are not limitedto, recordable type media such as volatile and non-volatile memorydevices 810, floppy and other removable disks, hard disk drives, opticaldisks (e.g., Compact Disk Read-Only Memory (CD ROMS), Digital VersatileDisks, (DVDs)), and transmission type media such as digital and analogcommunication links.

The network adapter 812 enables the computing system 800 to mediate datain a network 814 with an entity that is external to the computing device800, through any known and/or convenient communications protocolsupported by the computing system 800 and the external entity. Thenetwork adapter 812 can include one or more of a network adaptor card, awireless network interface card, a router, an access point, a wirelessrouter, a switch, a multilayer switch, a protocol converter, a gateway,a bridge, bridge router, a hub, a digital media receiver, and/or arepeater.

The network adapter 812 can include a firewall which can, in someembodiments, govern and/or manage permission to access/proxy data in acomputer network, and track varying levels of trust between differentmachines and/or applications. The firewall can be any number of moduleshaving any combination of hardware and/or software components able toenforce a predetermined set of access rights between a particular set ofmachines and applications, machines and machines, and/or applicationsand applications, for example, to regulate the flow of traffic andresource sharing between these varying entities. The firewall mayadditionally manage and/or have access to an access control list whichdetails permissions including for example, the access and operationrights of an object by an individual, a machine, and/or an application,and the circumstances under which the permission rights stand.

Other network security functions can be performed or included in thefunctions of the firewall, can include, but are not limited to,intrusion-prevention, intrusion detection, next-generation firewall,personal firewall, etc.

As indicated above, the techniques introduced here implemented by, forexample, programmable circuitry (e.g., one or more microprocessors),programmed with software and/or firmware, entirely in special-purposehardwired (i.e., non-programmable) circuitry, or in a combination orsuch forms. Special-purpose circuitry can be in the form of, forexample, one or more application-specific integrated circuits (ASICs),programmable logic devices (PLDs), field-programmable gate arrays(FPGAs), etc.

Remarks

The foregoing description of various embodiments of the claimed subjectmatter has been provided for the purposes of illustration anddescription. It is not intended to be exhaustive or to limit the claimedsubject matter to the precise forms disclosed. Many modifications andvariations will be apparent to one skilled in the art. Embodiments werechosen and described in order to best describe the principles of theinvention and its practical applications, thereby enabling othersskilled in the relevant art to understand the claimed subject matter,the various embodiments, and the various modifications that are suitedto the particular uses contemplated.

Although the Detailed Description describes certain embodiments and thebest mode contemplated, no matter how detailed the above appears intext, the embodiments can be practiced in many ways. Details of thesystems and methods may vary considerably in their implementationdetails, while still being encompassed by the specification. As notedabove, particular terminology used when describing certain features oraspects of various embodiments should not be taken to imply that theterminology is being redefined herein to be restricted to any specificcharacteristics, features, or aspects of the invention with which thatterminology is associated. In general, the terms used in the followingclaims should not be construed to limit the invention to the specificembodiments disclosed in the specification, unless those terms areexplicitly defined herein. Accordingly, the actual scope of theinvention encompasses not only the disclosed embodiments, but also allequivalent ways of practicing or implementing the embodiments under theclaims.

The language used in the specification has been principally selected forreadability and instructional purposes, and it may not have beenselected to delineate or circumscribe the inventive subject matter. Itis therefore intended that the scope of the invention be limited not bythis Detailed Description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of variousembodiments is intended to be illustrative, but not limiting, of thescope of the embodiments, which is set forth in the following claims.

The invention claimed is:
 1. A lamp control system comprising: a logicmodule that includes an interface configured to couple with a lightingsource having multiple color channels, non-volatile memory configured tostore a color model, a processor configured to compute flux ratios fromthe multiple color channels based on the color model, and a controlsignal driver configured to send the computed flux ratios as controlsignals to the lighting source via the interface; and a light emittingdiode-based (LED-based) lamp that includes an interface configured tocouple with the logic module, two or more color strings, each colorstring comprising one or more light emitting diodes (LEDs) of asubstantially similar color, non-volatile memory configured to store atleast one spectral power density (SPD) distribution summarycharacterizing each color string, an optical sensor configured tomeasure brightness levels of the two or more color strings, and aprocessor configured to send at least a subset of the measuredbrightness levels and the SPD distribution summaries to the logic modulevia the interface.
 2. The lamp control system of claim 1, wherein thelogic module further includes: a power driver configured to providepower to the LED-based lamp via the interface.
 3. The lamp controlsystem of claim 1, wherein the LED-based lamp includes a power source.4. The lamp control system of claim 1, wherein the optical sensor of theLED-based lamp measures brightness of the two or more color strings oneat a time by sequentially illuminating each color string for a specifiedamount of time.
 5. The lamp control system of claim 1, wherein theprocessor of the logic module is further configured to: detect when abrightness level of a color string of the LED-based lamp has experienceda change; and in response to detecting the change, recalibrate acorresponding color model based on the brightness level of the colorstring and a corresponding SPD distribution summary.
 6. A lamp controlsystem comprising: a driverless light emitting diode-based (LED-based)lamp that includes one or more color strings, each color stringcomprising one or more light emitting diodes (LEDs) of a substantiallysimilar color, and an optical sensor configured to generate readingsspecifying a brightness level of each of the one or more color strings;and a logic module that includes non-volatile memory configured to storea color model, a processor configured to determine appropriateadjustments for the driverless LED-based lamp based at least in part onthe color model, the optical sensor readings, and one or more spectralpower density (SPD) distribution summaries for the one or more colorstrings, and a control signal driver configured to send the appropriateadjustments as control signals to the driverless LED-based lamp.
 7. Thelamp control system of claim 6, wherein the one or more SPD distributionsummaries for the one or more color strings are stored withinnon-volatile memory of the driverless LED-based lamp.
 8. The lampcontrol system of claim 7, wherein the one or more SPD distributionsummaries are stored in a quantized integer format.
 9. The lamp controlsystem of claim 6, wherein the one or more SPD distribution summariesfor the one or more color strings are stored within cloud-based memorythat is accessible to the logic module.
 10. The lamp control system ofclaim 6, wherein the logic module further comprises a power driverconfigured to provide electric current to the LED-based lamp.
 11. Thelamp control system of claim 10, wherein the driverless LED-based lampdistributes the electric current to the one or more color strings basedon the control signals provided by the control signal driver.
 12. Thelamp control system of claim 6, wherein the driverless LED-based lampincludes an interface for receiving a first end of a ribbon cable, andwherein the logic module includes an interface for receiving a secondend of the ribbon cable.
 13. The lamp control system of claim 12,wherein the ribbon cable includes a first wire channel corresponding toa color channel in the driverless LED-based lamp and a second wirechannel corresponding to a feedback channel for sending information fromthe driverless LED-based lamp to the logic module.
 14. The lamp controlsystem of claim 13, wherein the information includes the optical sensorreadings and the one or more SPD distribution summaries that are storedwithin non-volatile memory of the driverless LED-based lamp.
 15. Thelamp control system of claim 6, wherein each SPD distribution summarycharacterizes a corresponding color string with tristimulus valuesacross various operating characteristics.
 16. The lamp control system ofclaim 15, wherein the various operating characteristics includedifferent electric current values and different temperature values. 17.The lamp control system of claim 6, wherein each SPD distributionsummary includes a thermal matrix that characterizes thermal cross-talkbetween adjacent light sources in a corresponding color string andcapacity characteristics of the adjacent light sources in thecorresponding color string.
 18. The lamp control system of claim 17,wherein the thermal matrix is provided to the logic module by thedriverless LED-based lamp when re-calibrating the color model.
 19. Thelamp control system of claim 6, wherein the color model specifies aplurality of optimized flux ratios of the one or more color strings thatproduce a specific correlated color temperature at a given operatingtemperature.
 20. The lamp control system of claim 6, wherein the controlsignals are represented as digitized commands or as analog valuesrepresented by an electrical voltage or current.
 21. A methodcomprising: generating a color model for a light emitting diode-based(LED-based) lamp having multiple color strings by creating a series ofspectral power density (SPD) distribution summaries for each colorstring, wherein each SPD distribution summary characterizes a particularcolor string at a certain set of operating conditions; storing theseries of SPD distribution summaries in a non-volatile memory of theLED-based lamp; determining a current operating condition of theLED-based lamp; identifying a particular SPD distribution summarycorresponding to the current operating condition; transmitting thecurrent operating condition and the particular SPD distribution summaryto a logic module coupled to the LED-based lamp; identifying, by thelogic module, a corrective adjustment for at least one of the multiplecolor strings based on the current operating condition and theparticular SPD distribution summary; transmitting, by the logic module,a control signal representing the corrective adjustment to the LED-basedlamp.
 22. The method of claim 21, wherein the series of SPD distributionsummaries are stored in the non-volatile memory of the LED-based lamp ina reduced file format.
 23. The method of claim 21, wherein each colorstring includes one or more light emitting diodes (LEDs) of asubstantially similar color.
 24. The method of claim 21, wherein thecurrent operating condition specifies a temperature value, an electriccurrent value, or both.